Bouncing cosmology in a curved braneworld

TL;DR

This paper investigates a non-singular bouncing universe within a warped braneworld model featuring dynamical branes and a non-zero brane cosmological constant, showing compatibility with observational data.

Contribution

It introduces a radion-based bouncing cosmology in a curved braneworld with a phantom-like kinetic term, providing a novel mechanism for a non-singular bounce.

Findings

The model produces a non-singular bounce through radion dynamics.

Primordial perturbations match Planck satellite constraints.

The radion transitions from normal to phantom regime during evolution.

Abstract

We explore the possibility of a non-singular bounce in our universe from a warped braneworld scenario with dynamical branes and a non-zero brane cosmological constant. Such models naturally incorporate a scalar sector known as the radion originating from the modulus of the theory. The presence of brane cosmological constant renders the branes to be non-flat and gives rise to a potential and a non-canonical kinetic term for the radion field in the four dimensional effective action. The kinetic term exhibits a phantom-like behavior within the domain of evolution of the modulus which leads to a violation of the null-energy condition often observed in a bouncing universe. The interplay of the radion potential and kinetic term enables the evolution of the radion field from a normal to a phantom regime where the universe transits from a contracting era to an expanding epoch through a non-singular bounce. Analysis of the scalar and tensor perturbations over such background evolution reveal that the primordial observables e.g., the amplitude of scalar perturbations $\mathcal{A}_s$, tensor to scalar ratio $r$ and the scalar spectral index $n_s$ are in agreement with the current constraints reported by the Planck satellite. The implications are discussed.